include<tools/util.scad>
$fn=100;
//书挡主体
difference(){
    union(){
        translate([-40,0,0]) cube([40,140,4]);
            cube([4,140,125]);

        cube([100,140,1.5]);
        translate([0,25,125]) rotate([0,90,0]) 
        d_2_circle_slot(radius=25,height=4,width=90);
        }
    translate([-0.5,45,25]) 
    union(){
        cube([5,50,75]);
        translate([0,25,75]) rotate([0,90,0]) cylinder(h=5,d=50);
    }
}
//书挡下圆角
translate([100,140,0])
rotate([90,0,0])
d_arc_cylinder(radius=1.5,height=140,angle=90);
//小加强筋
translate([0,68,0])
rotate([0,90,90])
linear_extrude(4)
polygon([[0,0],[-20,0],[0,15]]);